R.W. Fernstrum & Company

Product Catalog

GRIDCOOLER®

KEEL COOLER

TABLE OF CONTENTS

INTRODUCTION

KEEL COOLING TEChNOLOGy

ENGINEERED TO COOL

MATERIALS

DESIGN FLEXIBILITy

STACKED GRIDCOOLER KEEL COOLER

ANGLED TUBE GRIDCOOLER KEEL COOLER

INSTALLATION

RECOMMENDATION INFORMATION

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yOUR SOLUTION IS OUR COMMITMENT

R.W. Fernstrum & Company has been engineering and manufacturing

custom heat exchangers for the marine industry since 1949. Each cooling

solution is engineered to meet the requirements of your engine, vessel,

and operating conditions. Our commitment to quality means you get a

reliable, long-lasting cooling system from Fernstrum®, the pioneer of the

rectangular tube keel cooler.

The GRIDCOOLER® Keel Cooler has continually evolved to meet the

performance expectations of naval architects and the marine industry

worldwide. Our team of craftsmen employ the latest technologies to

maximize our manufacturing process. The result is a custom-designed

GRIDCOOLER Keel Cooler solution that performs as expected, meeting

your exact needs.

Fernstrum set the standard in marine heat exchangers over 65 years

ago, building a reputation focused on innovation. Today, we continue

our commitment to constant improvement, ensuring you have quality,

reliability, and the latest in cooling technology on your side.

Contact our sales and engineering team for expert advice on cooler

sizing, placement, installation, and service. We’re excited to welcome

you to the ever-growing Fernstrum family.

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KEEL COOLING

Advantages Compared to an open circuit cooling system (inboard heat exchanger),

a closed circuit cooling system provides several distinct advantages.

A closed circuit cooling system eliminates the need for an inboard heat

exchanger, raw water pumps, strainers, seawater piping, and the high

maintenance associated with open circuit cooling systems. It also eliminates

silt and sand buildup in the cooling circuit and protects the system from

salt water corrosion. The use of a keel cooler eliminates the need for

seawater to enter the hull. From an environmentally friendly perspective,

keel cooling provides a zero discharge solution eliminating the possibility

of contaminants entering the seawater.

Keel Cooling Helps Eliminate

• High Maintenance• Raw Water Pumps• Sand & Silt Buildup• Seacock• Seawater Circuit• Seawater Piping• Strainers

FIGURE I: How Keel Cooling Works

The GRIDCOOLER® Keel Cooler is mounted externally on the hull below the waterline. The engine coolant

is circulated through the GRIDCOOLER Keel Cooler, which transfers heat from the coolant before it returns

to the engine. The keel cooler is in constant contact with seawater to efficiently transfer heat.

Keel Cooling TechnologyA keel cooler is a closed circuit cooling system mounted externally on the vessel’s hull below the waterline. The

concept of keel cooling is similar to the application of a radiator on a car. Engine coolant is circulated through the

keel cooler, which transfers heat from the coolant before it returns to the engine. The keel cooler is in constant

contact with seawater allowing the cooling system to efficiently transfer heat between the coolant and seawater

(please see Figure I for an illustration).

heat Source

hull

GRIDCOOLER Keel Cooler

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ENGINEERED TO COOL

Marine Applications

The GRIDCOOLER® Keel Cooler is a custom made cooling system engineered to meet the specific demands of the

engine manufacturer and operating conditions of your vessel. With over 65 years of experience in keel cooling,

our sales and engineering team can help provide a reliable cooling solution to meet your specific needs.

• Air Conditioning Units

• Bow Thrusters

• Compressors

• Electrical Equipment

• Generator Sets

• hydraulics

• Land Based Applications

• Propulsion & Auxiliary Engines

• Pumps

• Reduction Gears

• Winches

Heat Source

• ATB

• Barges

• Commercial Fishing

• Dredges

• Ferries

• Landing Craft

• Life Boats

• OSV

• Passenger Vessels

• Patrol Boats

• Pilot Boats

• PSV

• Push Boats

• Recreational Boats

• Semi-Submersibles (ATV & ROV)

• Tug Boats

• Buoys

• Drainage Systems

• Facilities’ Climate Control

• hydroelectric Plants

• Irrigation Systems

• Lift Stations

• Offshore Wind Generators

• Pump Station Engines

• Storm Sewer Systems

• Wave & Tidal Generators

Stationary & Industrial Applications

The application lists provided are only partial lists. If you have an application outside of these parameters, our sales and engineering team may be able to help provide a solution. Please call 906.863.5553 or email sales@fernstrum.com.

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90/10 Copper-Nickel The copper-nickel GRIDCOOLER Keel Cooler is crafted using heavy walled

rectangular 90/10 copper-nickel tubing. This alloy was selected based on

its durability, heat exchange abilities, resistance to salt water corrosion,

and natural antifouling capabilities.

The GRIDCOOLER® Keel Cooler is a completely assembled unit and is factory tested to ensure dependability.

The rectangular shaped tubing used in its construction is structurally sound and provides a higher heat transfer

rate than round tubing.

Fernstrum provides premium materials to help maximize your cooling system:

Available in 3 sizes

DC

B

Enhanced & Smooth Interior Walled Tubing Fernstrum® offers two types of surfaces on the interior of the copper nickel tubing,

smooth or enhanced. The enhanced surface, a Fernstrum exclusive, is a truncated

cone pattern on the interior of the tube generating greater heat transfer. Compared

to a smooth walled tube, the enhanced tube increases the heat transfer capability

by up to 30 percent. This is especially true in applications where glycol solutions

are utilized. The improvement in efficiency may reduce the number or size of the

units required for an application.

Note: The interior surface of the tubing is determined based on your cooling

requirements.

Smooth Surface

Enhanced Surface

MATERIALS

5000 Series Aluminum The aluminum GRIDCOOLER Keel Cooler is designed specifically for unpainted

aluminum hull applications in fresh or cold seawater environments. 5000 series

aluminum alloy was selected based on its compatibility with unpainted aluminum

hulls and saltwater corrosion resistance. The alloy compatibility between the hull

and keel cooler prevents pitting and avoids potential damage from interacting

metals. Aluminum units are tig welded for durability.

Aluminum GRIDCOOLER Keel Cooler

Silver Braze WireEach copper-nickel keel cooler is torch brazed with 56% silver (content) braze wire

to maximize the flexibility and durability of the unit. The higher silver content offers

superior corrosion resistance, improving the dependability of the keel cooler and its

ability to withstand harsher operating conditions. Critical braze joints are ultrasonically

tested as an added measure to ensure the unit’s reliability.

Brazing

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The GRIDCOOLER® Keel Cooler is sized to meet your engine’s cooling requirements and operating environment.

Our team will work with you to recommend features to optimize the functionality of your cooling system.

The following examples show a few of the more common configurations. Additional configurations are available

upon request.

One Piece Header DesignFernstrum® has continually evolved the GRIDCOOLER Keel Cooler’s design to improve efficiency and dependability.

The rectangular one piece header design has fewer joints for improved durability and provides greater flexibility in

custom cooling solutions.

Single- & Multi-Pass DesignsFernstrum offers a range of single- and multi-pass designs to help optimize your cooling solution. These designs

maximize the efficiency of the engine coolant flow, allowing for a more compact solution.

ILLUSTRATION: Single- & Multi-Pass Designs

Nozzles on a single-pass design are located on opposite ends of the keel cooler; whereas, the nozzles on a

multi-pass design are located on the same end of the unit.

Single-Pass DesignStandard Through-hull Standard Through-hull

Multi-Pass Design

E1 SERIES units place the zinc anodes and drain

plugs on the end of the keel cooler reducing the hull

projection; a benefit to high-speed craft and fishermen

where entanglement of nets and/or lines is a concern.

HD SERIES stiffener plates can be added to units

providing additional support to prevent tubes from

bowing, bending, or vibrating from the impact of heavy

seas. These plates do not have additional mounting

points. The hD Series is ideally suited for applications

where the vessel is operating in heavy pounding seas,

strong currents, or the keel cooler is positioned near

the bow of the vessel.

DESIGN FLEXIBILITy

Bottom Mounted Zinc Anodes & Drain Plugs

Nozzles

Nozzles

Additional Stiffener Plates

End Mounted Zinc Anodes & Drain Plugs

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Z SERIES flanges relocate the connecting and mating points to the hull’s exterior, eliminating hull penetrations.

The typical through-hull nozzle mounting connections are replaced with a flange. Mating flanges are provided

in carbon or stainless steel. Additional mounting hardware is also supplied for isolation. This design is ideal for

installations where mounting hardware cannot be easily accessed from the interior of the hull, easing installation

on double hulled vessels and may eliminate the need for cofferdams. L Series support plates are standard in

this configuration.

Flange

L SERIES support plates are designed to minimize intermediate support bolt hull penetrations. These support

plates extend beyond the keel cooler side tubes, providing additional securing options. This feature is especially

useful in retrofitting a keel cooler to an existing vessel.

Single-Pass L SERIES

Single-Pass Z SERIES Multi-Pass Z SERIES

header Support Plate

Multi-Pass L SERIES

DESIGN FLEXIBILITy

Intermediate Support Plate

Flange

Flanges

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• Bending and/or Twisting of Unit

• Extended Nozzle(s)

• Mounting Foot Pad(s)

• Side Venting

• Support Plates Available on

the Top or Bottom of the Unit

• Vented Stud(s)

Additional Customization Options

*Additional designs are available upon request.

Angled Tube GRIDCOOLER Keel CoolerAn angled tube GRIDCOOLER Keel Cooler optimizes the heat transfer for side mounted zero knot or stationary

applications. The design exploits the natural convection current created by the heat exchanger. The unique position

and angle of the tubes are crafted to maximize the flow of raw water between the tubes. This configuration also

resists the collection of silt and other debris from building up on the unit.

Angled Tube GRIDCOOLER Keel Cooler

ILLUSTRATION: Angled Tube GRIDCOOLER Keel Cooler

The angled tube GRIDCOOLER Keel Cooler’s tubes are

positioned to enhance and exploit the natural convection

current generated by the heat exchanger.

Stacked GRIDCOOLER Keel CoolerWhen faced with limited space or larger cooling

requirements, a stacked GRIDCOOLER® Keel Cooler

reduces the footprint of the keel cooler while

providing greater heat transfer. The design is ideal

for cooling larger engines, reducing the number of

units required, or fitting into an existing application

in the case of repowering. Double Stacked GRIDCOOLER Keel Cooler

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Our expert engineers and sales team will help you determine the best installation solution. Please note the operating

conditions and hull design of a vessel weigh heavily on how a unit is installed. Shown below are a few common

installations for a GRIDCOOLER® Keel Cooler.

Recessed Recessing a GRIDCOOLER Keel Cooler streamlines the installation and provides significant protection from potential

damage. Independent tests conducted at the Vienna Model Test Basin have shown that drag is negligible when the

unit is recessed into a ship’s hull. The position of the recess can be located on the side or bottom of the hull. This

type of installation is common in new projects and ideal for fast-moving vessels.

External An external installation typically applies fairing and side plates for added protection and to improve streamlining.

This mounting option is commonly used in retro-fitting projects.

Side Mounted Mounting the GRIDCOOLER Keel Cooler on the side of the hull prevents potential damage to the unit. It is ideal

for situations where a keel cooler cannot be mounted to the bottom of the hull.

Note: When recessing the unit into the side of the hull for generator sets and/or equipment operating at dockside,

angle the top of the recess box to allow convection current over the cooler.

INSTALLATION

Recessed

External Mount

Side Mount - Propulsion

Recessed

Preformed

Side Mount - Propulsion

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Our team will need the following specifications to make a proper product recommendation.

Please visit our website at fernstrum.com to fill out or download a recommendation form.

RECOMMENDATION INFORMATION

Engine Information• Engine Type (Propulsion, Bow Thruster, Generator, Other)

• Emissions Data (Tier 1, 2, 3, or IMO)

• Engine Manufacturer

• Model

• Rating (BhP / RPM, BKW / RPM, EKW / RPM)

• Engine Age

• Percentage of Antifreeze Used

• heat Rejection

• Fresh Water Flow Rate

• Fresh Water Temp Into Cooler

• Fresh Water Temp Out or Drop Across Cooler

Reduction Gear Information• Make & Model of Gear

Vessel Information• Type of Vessel (e.g., Ferry, Trawler, Pleasure Boat)

• hull Construction (Steel, Fiberglass, Wood, Aluminum Painted/Unpainted)

• Minimum hull Speed at Full Rated Power (Under Full Load)

• Cofferdam Installation

Environmental Conditions• Maximum Sea Water Temp

fernstrum.comPhone: 906.863.5553 • Fax: 906.863.5203 • Email: sales@fernstrum.com

P.O. Box 97 • 1716 11th Avenue • Menominee, Michigan 49858 • USA

© 2013 R.W. Fernstrum & Company. All rights reserved. FERNSTRUM® and GRIDCOOLER® are registered trademarks of R.W. Fernstrum & Company.